The results could lead to a fundamental change in understanding relationship formation - and it sounds a warning for the idea that couples can change each other over time, researchers said.

The study found that people in relationships do not change each other over time. Instead, the evidence places new emphasis on the earliest moments of a relationship – showing that future friends or partners are already similar at the outset of their social connection, researchers said.

Whether or not a relationship develops could depend on the level of similarity the two individuals share from the beginning of their meeting.

The study has major implications for how to grasp the foundations of relationships and approach relationships when the partners are different, researchers said.

The findings were published in the Journal of Personality and Social Psychology.